1. Field of the Invention
The present invention relates to an ink jet recording apparatus, and more particular, a recording head cleaning device for high-speed ink jet printers, capable of recording a high grade picture image with high reliability, and a printer provided with the head cleaning device.
2. Description of the Related Art
Line scanning type ink jet printers have been proposed as ink jet printers for printing on a recording medium (for example, a continuous recording paper form, or continuously conveyed cut sheets). This apparatus comprises a lengthy ink jet recording head, on which nozzle holes for discharge of ink drops are arranged in a row, and which are opposed to a widthwise surface (substantially perpendicular to a direction of sheet conveyance) of a continuous recording paper form over an entire width, and selectively controls impact of ink drops, which are discharged from the nozzle holes, on the recording paper surface according to a recording signal. At the same time, main scanning is performed while the recording paper form is moved at high speed in a longitudinal direction of the continuous recording paper form. By virtue of the main scanning and control of impact of ink drops on the recording paper form, formation of recording dots on scanning lines is controlled, thus obtaining a recording picture image on the recording paper form.
As such line scanning type ink jet printers, there have been many of apparatuses making use of a continuous ink jet type recording head as a recording head, and apparatuses making use of an on-demand ink jet type recording head as a recording head. Among these, on-demand ink jet type line-scanning ink jet printers are inferior to continuous ink jet type apparatuses in recording speed but superior thereto in high-definition recording performance and are simple in ink system, so that they are suitable for provision of widespread type high-definition color high-speed printers.
A recording head for such on-demand ink jet type line-scanning ink jet printers comprises a line type one, in which a multiplicity of nozzles are arranged in a row, and a drive voltage is applied to a piezoelectric element, or a heating element to apply pressure to ink in an ink chamber, which are opened at nozzle holes, to discharge ink drops (for example, JP-A-2001-47622).
By the way, the on-demand ink jet type printers need a recording head cleaning device to clean the neighborhood of nozzle holes. This cleaning device serves to remove ink made high in viscosity by virtue of being dried, affected ink, paper dust, etc., adhered to the neighborhood of nozzle holes, thus ensuring stability in discharge of ink.
As conventional recording head cleaning devices, there is known a nozzle cleaning device A to perform a so-called purging action, in which, for example, caps are brought into close contact with all nozzle holes of a recording head to suck ink, and to thereafter perform a so-called wiping action, in which an orifice surface formed with the nozzle holes is wiped off by a wiping member made of rubber or the like. Such cleaning device A involves the following disadvantages.    (1) Since it is necessary to repeat a cleaning action several times in order to remove dust and ink firmly adhered to nozzle holes and their neighborhood, it takes much time and removal is in some cases difficult.    (2) Foreign matters are in some cases pushed into the nozzle holes in the wiping action. Such inconvenience is liable to occur when the wiping member becomes dirty.    (3) Since the multiplicity of nozzle holes are acted by negative press at a time, a sufficient amount of ink cannot flow through the faulty nozzles having a large flow resistance due to plugging of foreign matters or the like.    (4) A large amount of ink is consumed in the purging action.
As a cleaning device to improve the disadvantage (1), a cleaning device B has been proposed, in which a cleaning fluid spray nozzle is provided in the neighborhood of nozzle holes to spray a pressurized cleaning fluid for cleaning in order to remove dust and ink firmly adhered to the nozzle holes and their neighborhood in a short time (for example, JP-A-8-150710).
As a cleaning device to improve the disadvantage (2), a cleaning device C has been proposed, in which a wiping member having been made dirty when wiping off ink adhered to the neighborhood of nozzles is cleaned in a cleaning fluiding tank storing a cleaning fluid to clean the dirt (for example, JP-A-2002-19132).
As a cleaning device to improve the disadvantages (3) and (4), an individual nozzle cleaning device D has been disclosed, in which a suction port is provided to be opposed to a part of nozzle holes among a row of nozzle holes and the suction port is moved along the row of nozzle holes to perform cleaning without direct contact with the nozzle holes (for example, JP-A-2001-260392).
The disadvantages (1) to (4) involved in cleaning devices can be alleviated by combining the cleaning device B and the cleaning device C with the conventional individual nozzle cleaning device D.
However, the cleaning device B involves the following disadvantage.    (5) Spraying of the cleaning fluid in some cases causes entry of the cleaning fluid and bubbles from the nozzle holes to bring about failure in discharge of nozzles. The device is made complex by virtue of disposal of scattered cleaning fluid.
On the other hand, the cleaning device C involves the following disadvantage.    (6) It takes time in moving the wiping member to the cleaning tank to clean the same. In particular, in case of cleaning a line head, the wiping member is liable to become dirty because of cleaning of a multiplicity of nozzles, so that it is necessary to frequently move the wiping member in the course of the purging and wiping actions and it takes time in cleaning, which leads to substantial reduction in recording speed of the printer.